1. Field of the Invention
This invention relates to surgical instruments and, more particularly, to an optical instrument for forming an incision in vascularized tissues and photocoagulating tissue adjacent the incision which has the operating feel similar to a conventional cold scalpel.
2. Description of the Prior Art
A significant problem associated with surgical incisions is the control of bleeding. The problem is particularly acute for surgical removal of burn wound eschar and in surgery of highly vascularized organs such as the liver.
An important factor in the development of burn wound sepsis is the dead tissue of deeply burned areas which completely lose their resistance to invading bacteria. It has long been recognized that prompt, safe removal of the dead tissue is desirable not only to prevent infection but also to promote more rapid wound cover with autograft or homograft. Attempts to remove dead tissue by chemical and surgical means have been made. Surgical removal has been carried out effectively, but with the attendant drawback of large blood losses necessitating extensive transfusions. Therefore, the immediate and complete surgical excision of deep burns is generally limited to patients with moderate sized burns. In summary, earlier grafting is capable of markedly decreasing the incidence of bacterial wound sepsis, diminishing the hypermetabolic response of the severely-burned patient thereby resulting in a shortened hospital admission and allowing improved functional and cosmetic results.
Similar problems are associated with surgery on highly vascularized organs. Massive hemorrhage is sometimes a complication from small resections or even biopsies of the liver.
The use of focused laser radiation to incise and coagulate tissue has been widely considered, although such techniques have not been altogether satisfactory. Surgeons are generally accustomed to the tactile feedback that conventional tissue contacting scalpels provide, and they are reluctant to utilize an operating technique in which the surgical instrument is held above and apart from the tissue to be cut. Additionally, it is often difficult to accurately position the laser radiation. Inadvertent deposition of laser radiation away from the incision line may thus cause thermal necrosis to viable cells.
Another surgical device which attempts to simultaneously incise and coagulate tissue is the diathermy scalpel which utilizes high-frequency electrical current for hemostatic incisions. The principal disadvantage of this device is its inadequate hemostasis in several types of surgery. Other disadvantages include unwanted thermal necrosis and hazards associated with electrical shocks. Furthermore, there may be some tendency for the diathermy electrode to adhere to highly-vascularized organs since removal of an electrocoagulating electrode from the cut surface of a liver has, in some cases, reactivated bleeding.
Hemostatic incisions have also been attempted using a plasma scalpel in which a stream of high-temperature gases are directed at the tissue surface in order to form the incision and coagulate tissue adjacent the incision. It has been suggested that plasma scalpels also exhibit slow excision rates and thermal necrosis. Furthermore, plasma gas embolization has been reported following surgery with the plasma scalpel.